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过去十年来,对储层岩心样品进行了多次地质力学试验的研究,从而对储层力学性质有了深入了解。这些试验主要目的在于测量压缩系数、热膨胀系数以及应力—应变—强度性质。传统上,进行两类地质力学试验:单轴压缩试验和三轴试验。然而,要对地质力学试验结果进行解释则必须对试验有充分的了解。在此发表了有关试验程序及对各类型试验结果的简短总结。典型的地质力学试验对油藏砂岩的试验结果将用来评价储层性质。 文中用了若干压缩系数定义,如岩石压缩系数、体积压缩系数、孔隙压缩系数、颗粒(固体)压缩系数以及流体压缩系数等。类似的定义也用于热体积变化,文中也推导出了以有效应力表示这些压缩系数的方程。对于砂岩和许多岩石,这些材料性质不是常数,而是随地层有效应力大小和所遵循的应力路径而变化。为了确定这些压缩系数在地下的数值,必须用能够模拟地下应力路径的试验设备和试验程序。对常规热体积改变方程的分析,揭示了其基本假设有误,并给出了修正方程。
Over the past decade, many studies of geomechanical tests have been conducted on reservoir core samples to gain insight into reservoir mechanics. The main purpose of these tests is to measure the compressibility, coefficient of thermal expansion and stress-strain-strength properties. Traditionally, two types of geomechanical tests have been performed: uniaxial compression tests and triaxial tests. However, to interpret the results of the geomechanical test you must have a good understanding of the test. Here is a brief summary of the test procedure and the results of each type of test. The results of typical geomechanical tests on reservoir sandstones will be used to evaluate reservoir properties. Several definitions of compressibility factors are used in this paper, such as rock compressibility, volumetric compressibility, pore compressibility, particle (solid) compressibility and fluid compressibility. A similar definition is also used for thermal volume changes, and equations for these compressibility coefficients are also derived in terms of effective stress. For sandstone and many rocks, the properties of these materials are not constant, but vary with the effective stress of the formation and the stress path to be followed. In order to determine the value of these compression factors underground, test equipment and test procedures capable of simulating underground stress paths must be used. The analysis of the conventional heat volume change equation reveals that the basic assumptions are incorrect and the correction equation is given.